[Macros] Use source locations to determine whether to suppress macro expansions.

include/swift/AST/ASTScope.h

@@ -218,6 +218,10 @@ class ASTScopeImpl : public ASTAllocated<ASTScopeImpl> {
     return nullptr;
   }
 
+  virtual NullablePtr<MacroExpansionDecl> getFreestandingMacro() const {
+    return nullptr;
+  }
+
 #pragma mark - debugging and printing
 
 public:
@@ -278,6 +282,10 @@ class ASTScopeImpl : public ASTAllocated<ASTScopeImpl> {
   static std::pair<CaseStmt *, CaseStmt *>
   lookupFallthroughSourceAndDest(SourceFile *sourceFile, SourceLoc loc);
 
+  static void lookupEnclosingMacroScope(
+      SourceFile *sourceFile, SourceLoc loc,
+      llvm::function_ref<bool(ASTScope::PotentialMacro)> consume);
+
   /// Scopes that cannot bind variables may set this to true to create more
   /// compact scope tree in the debug info.
   virtual bool ignoreInDebugInfo() const { return false; }
@@ -840,24 +848,20 @@ class DefaultArgumentInitializerScope final : public ASTScopeImpl {
   bool ignoreInDebugInfo() const override { return true; }
 };
 
-/// Consider:
-///  @_propertyWrapper
-///  struct WrapperWithInitialValue {
-///  }
-///  struct HasWrapper {
-///    @WrapperWithInitialValue var y = 17
-///  }
-/// Lookup has to be able to find the use of WrapperWithInitialValue, that's
-/// what this scope is for. Because the source positions are screwy.
-
-class AttachedPropertyWrapperScope final : public ASTScopeImpl {
+/// The scope for custom attributes and their arguments, such as for
+/// attached property wrappers and for attached macros.
+///
+/// Source locations for the attribute name and its arguments are in the
+/// custom attribute, so lookup is invoked from within the attribute
+/// itself.
+class CustomAttributeScope final : public ASTScopeImpl {
 public:
   CustomAttr *attr;
-  VarDecl *decl;
+  Decl *decl;
 
-  AttachedPropertyWrapperScope(CustomAttr *attr, VarDecl *decl)
+  CustomAttributeScope(CustomAttr *attr,Decl *decl)
       : attr(attr), decl(decl) {}
-  virtual ~AttachedPropertyWrapperScope() {}
+  virtual ~CustomAttributeScope() {}
 
 protected:
   ASTScopeImpl *expandSpecifically(ScopeCreator &) override;
@@ -871,7 +875,8 @@ class AttachedPropertyWrapperScope final : public ASTScopeImpl {
   NullablePtr<DeclAttribute> getDeclAttributeIfAny() const override {
     return attr;
   }
- bool ignoreInDebugInfo() const override { return true; }
+  bool ignoreInDebugInfo() const override { return true; }
+
 private:
   void expandAScopeThatDoesNotCreateANewInsertionPoint(ScopeCreator &);
 };
@@ -1134,9 +1139,9 @@ class SpecializeAttributeScope final : public ASTScopeImpl {
 class DifferentiableAttributeScope final : public ASTScopeImpl {
 public:
   DifferentiableAttr *const differentiableAttr;
-  ValueDecl *const attributedDeclaration;
+  Decl *const attributedDeclaration;
 
-  DifferentiableAttributeScope(DifferentiableAttr *diffAttr, ValueDecl *decl)
+  DifferentiableAttributeScope(DifferentiableAttr *diffAttr, Decl *decl)
       : differentiableAttr(diffAttr), attributedDeclaration(decl) {}
   virtual ~DifferentiableAttributeScope() {}
 
@@ -1270,6 +1275,10 @@ class MacroExpansionDeclScope final : public ASTScopeImpl {
   SourceRange
   getSourceRangeOfThisASTNode(bool omitAssertions = false) const override;
 
+  NullablePtr<MacroExpansionDecl> getFreestandingMacro() const override {
+    return decl;
+  }
+
 protected:
   void printSpecifics(llvm::raw_ostream &out) const override;
 

include/swift/AST/Decl.h

@@ -3899,7 +3899,7 @@ class NominalTypeDecl : public GenericTypeDecl, public IterableDeclContext {
   /// protocols to which the nominal type conforms. Furthermore, the resulting
   /// set of declarations has not been filtered for visibility, nor have
   /// overridden declarations been removed.
-  TinyPtrVector<ValueDecl *> lookupDirect(DeclName name,
+  TinyPtrVector<ValueDecl *> lookupDirect(DeclName name, SourceLoc loc = SourceLoc(),
                                           OptionSet<LookupDirectFlags> flags =
                                           OptionSet<LookupDirectFlags>());
 
@@ -4454,7 +4454,8 @@ class ClassDecl final : public NominalTypeDecl {
       // Force loading all the members, which will add this attribute if any of
       // members are determined to be missing while loading.
       auto mutableThis = const_cast<ClassDecl *>(this);
-      (void)mutableThis->lookupDirect(DeclBaseName::createConstructor());
+      (void)mutableThis->lookupDirect(DeclBaseName::createConstructor(),
+                                      getStartLoc());
     }
 
     if (Bits.ClassDecl.ComputedHasMissingDesignatedInitializers)

include/swift/AST/DeclContext.h

@@ -598,7 +598,8 @@ class alignas(1 << DeclContextAlignInBits) DeclContext
   /// lookup.
   ///
   /// \returns true if anything was found.
-  bool lookupQualified(Type type, DeclNameRef member, NLOptions options,
+  bool lookupQualified(Type type, DeclNameRef member,
+                       SourceLoc loc, NLOptions options,
                        SmallVectorImpl<ValueDecl *> &decls) const;
 
   /// Look for the set of declarations with the given name within the
@@ -616,12 +617,12 @@ class alignas(1 << DeclContextAlignInBits) DeclContext
   ///
   /// \returns true if anything was found.
   bool lookupQualified(ArrayRef<NominalTypeDecl *> types, DeclNameRef member,
-                       NLOptions options,
+                       SourceLoc loc, NLOptions options,
                        SmallVectorImpl<ValueDecl *> &decls) const;
 
   /// Perform qualified lookup for the given member in the given module.
   bool lookupQualified(ModuleDecl *module, DeclNameRef member,
-                       NLOptions options,
+                       SourceLoc loc, NLOptions options,
                        SmallVectorImpl<ValueDecl *> &decls) const;
 
   /// Look up all Objective-C methods with the given selector visible

include/swift/AST/DiagnosticsSema.def

@@ -7188,6 +7188,10 @@ ERROR(macro_accessor_missing_from_expansion,none,
 ERROR(macro_init_accessor_not_documented,none,
       "expansion of macro %0 produced an unexpected 'init' accessor",
       (DeclName))
+ERROR(global_arbitrary_name,none,
+      "'%0' macros are not allowed to introduce arbitrary names "
+      "at global scope",
+      (StringRef))
 
 ERROR(macro_resolve_circular_reference, none,
       "circular reference resolving %select{freestanding|attached}0 macro %1",

include/swift/AST/Evaluator.h

@@ -208,18 +208,6 @@ class Evaluator {
   /// is treated as a stack and is used to detect cycles.
   llvm::SetVector<ActiveRequest> activeRequests;
 
-  /// How many `ResolveMacroRequest` requests are active.
-  ///
-  /// This allows us to quickly determine whether there is any
-  /// `ResolveMacroRequest` active in the active request stack.
-  /// It saves us from a linear scan through `activeRequests` when
-  /// we need to determine this information.
-  ///
-  /// Why on earth would we need to determine this information?
-  /// Please see the extended comment that goes with the constructor
-  /// of `UnqualifiedLookupRequest`.
-  unsigned numActiveResolveMacroRequests = 0;
-
   /// A cache that stores the results of requests.
   evaluator::RequestCache cache;
 
@@ -342,16 +330,6 @@ class Evaluator {
     return activeRequests.count(ActiveRequest(request));
   }
 
-  /// Determine whether there is any active "resolve macro" request
-  /// on the request stack.
-  ///
-  /// Why on earth would we need to determine this information?
-  /// Please see the extended comment that goes with the constructor
-  /// of `UnqualifiedLookupRequest`.
-  bool hasActiveResolveMacroRequest() const {
-    return numActiveResolveMacroRequests > 0;
-  }
-
 private:
   /// Diagnose a cycle detected in the evaluation of the given
   /// request.

include/swift/AST/ModuleNameLookup.h

@@ -62,7 +62,7 @@ void lookupInModule(const DeclContext *moduleOrFile,
                     DeclName name, SmallVectorImpl<ValueDecl *> &decls,
                     NLKind lookupKind, ResolutionKind resolutionKind,
                     const DeclContext *moduleScopeContext,
-                    NLOptions options);
+                    SourceLoc loc, NLOptions options);
 
 /// Performs a qualified lookup into the given module and, if necessary, its
 /// reexports, observing proper shadowing rules.

include/swift/AST/NameLookup.h

@@ -513,7 +513,7 @@ void lookupVisibleDecls(VisibleDeclConsumer &Consumer,
 ///
 /// \param CurrDC the DeclContext from which the lookup is done.
 void lookupVisibleMemberDecls(VisibleDeclConsumer &Consumer,
-                              Type BaseTy,
+                              Type BaseTy, SourceLoc loc,
                               const DeclContext *CurrDC,
                               bool includeInstanceMembers,
                               bool includeDerivedRequirements,
@@ -545,6 +545,15 @@ template <typename Result>
 void filterForDiscriminator(SmallVectorImpl<Result> &results,
                             DebuggerClient *debugClient);
 
+/// \returns The set of macro declarations with the given name that
+/// fulfill any of the given macro roles.
+SmallVector<MacroDecl *, 1>
+lookupMacros(DeclContext *dc, DeclNameRef macroName, MacroRoles roles);
+
+/// \returns Whether the given source location is inside an attached
+/// or freestanding macro argument.
+bool isInMacroArgument(SourceFile *sourceFile, SourceLoc loc);
+
 /// Call the given function body with each macro declaration and its associated
 /// role attribute for the given role.
 ///
@@ -816,6 +825,22 @@ class ASTScope : public ASTAllocated<ASTScope> {
   static std::pair<CaseStmt *, CaseStmt *>
   lookupFallthroughSourceAndDest(SourceFile *sourceFile, SourceLoc loc);
 
+  using PotentialMacro =
+      llvm::PointerUnion<FreestandingMacroExpansion *, CustomAttr *>;
+
+  /// Look up the scope tree for the nearest enclosing macro scope at
+  /// the given source location.
+  ///
+  /// \param sourceFile The source file containing the given location.
+  /// \param loc        The source location to start lookup from.
+  /// \param consume    A function that is called when a potential macro
+  ///                   scope is found. If \c consume returns \c true, lookup
+  ///                   will stop. If \c consume returns \c false, lookup will
+  ///                   continue up the scope tree.
+  static void lookupEnclosingMacroScope(
+      SourceFile *sourceFile, SourceLoc loc,
+      llvm::function_ref<bool(PotentialMacro macro)> consume);
+
   SWIFT_DEBUG_DUMP;
   void print(llvm::raw_ostream &) const;
   void dumpOneScopeMapLocation(std::pair<unsigned, unsigned>);

include/swift/AST/NameLookupRequests.h

@@ -461,7 +461,7 @@ class LookupInModuleRequest
   LookupInModuleRequest(
       const DeclContext *, DeclName, NLKind,
       namelookup::ResolutionKind, const DeclContext *,
-      NLOptions);
+      SourceLoc, NLOptions);
 
 private:
   friend SimpleRequest;
@@ -511,7 +511,7 @@ class ModuleQualifiedLookupRequest
 public:
   ModuleQualifiedLookupRequest(const DeclContext *,
                                ModuleDecl *, DeclNameRef,
-                               NLOptions);
+                               SourceLoc, NLOptions);
 
 private:
   friend SimpleRequest;
@@ -537,7 +537,7 @@ class QualifiedLookupRequest
 public:
   QualifiedLookupRequest(const DeclContext *,
                          SmallVector<NominalTypeDecl *, 4>,
-                         DeclNameRef, NLOptions);
+                         DeclNameRef, SourceLoc, NLOptions);
 
 private:
   friend SimpleRequest;
@@ -588,7 +588,7 @@ class DirectLookupRequest
                            TinyPtrVector<ValueDecl *>(DirectLookupDescriptor),
                            RequestFlags::Uncached|RequestFlags::DependencySink> {
 public:
-  DirectLookupRequest(DirectLookupDescriptor);
+  DirectLookupRequest(DirectLookupDescriptor, SourceLoc);
 
 private:
   friend SimpleRequest;

include/swift/AST/TypeCheckRequests.h

@@ -3249,6 +3249,9 @@ class UnresolvedMacroReference {
 public:
   UnresolvedMacroReference(FreestandingMacroExpansion *exp) : pointer(exp) {}
   UnresolvedMacroReference(CustomAttr *attr) : pointer(attr) {}
+  UnresolvedMacroReference(
+      llvm::PointerUnion<FreestandingMacroExpansion *, CustomAttr *> pointer)
+      : pointer(pointer) {}
 
   FreestandingMacroExpansion *getFreestanding() const {
     return pointer.dyn_cast<FreestandingMacroExpansion *>();

include/swift/Sema/ConstraintSystem.h

@@ -2910,7 +2910,8 @@ class ConstraintSystem {
   /// and no new names are introduced after that point.
   ///
   /// \returns A reference to the member-lookup result.
-  LookupResult &lookupMember(Type base, DeclNameRef name);
+  LookupResult &lookupMember(Type base, DeclNameRef name,
+                             SourceLoc loc);
 
   /// Retrieve the set of "alternative" literal types that we'll explore
   /// for a given literal protocol kind.

lib/AST/ASTContext.cpp

@@ -1072,8 +1072,8 @@ DECLTYPE *ASTContext::get##NAME##Decl() const { \
       /* Note: lookupQualified() will search both the Swift overlay \
        * and the Clang module it imports. */ \
       SmallVector<ValueDecl *, 1> decls; \
-      M->lookupQualified(M, DeclNameRef(getIdentifier(#NAME)), NL_OnlyTypes, \
-                         decls); \
+      M->lookupQualified(M, DeclNameRef(getIdentifier(#NAME)), SourceLoc(), \
+                         NL_OnlyTypes, decls); \
       if (decls.size() == 1 && isa<DECLTYPE>(decls[0])) { \
         auto decl = cast<DECLTYPE>(decls[0]); \
         if (isa<ProtocolDecl>(decl) \
@@ -1336,7 +1336,8 @@ ConcreteDeclRef ASTContext::getRegexInitDecl(Type regexType) const {
                 {Id_regexString, Id_version});
   SmallVector<ValueDecl *, 1> results;
   spModule->lookupQualified(getRegexType(), DeclNameRef(name),
-                            NL_IncludeUsableFromInline, results);
+                            SourceLoc(), NL_IncludeUsableFromInline,
+                            results);
   assert(results.size() == 1);
   auto *foundDecl = cast<ConstructorDecl>(results[0]);
   auto subs = regexType->getMemberSubstitutionMap(spModule, foundDecl);

lib/AST/ASTScope.cpp

@@ -60,6 +60,12 @@ std::pair<CaseStmt *, CaseStmt *> ASTScope::lookupFallthroughSourceAndDest(
   return ASTScopeImpl::lookupFallthroughSourceAndDest(sourceFile, loc);
 }
 
+void ASTScope::lookupEnclosingMacroScope(
+    SourceFile *sourceFile, SourceLoc loc,
+    llvm::function_ref<bool(PotentialMacro)> body) {
+  return ASTScopeImpl::lookupEnclosingMacroScope(sourceFile, loc, body);
+}
+
 #if SWIFT_COMPILER_IS_MSVC
 #pragma warning(push)
 #pragma warning(disable : 4996)
@@ -138,7 +144,7 @@ DEFINE_GET_CLASS_NAME(AbstractFunctionDeclScope)
 DEFINE_GET_CLASS_NAME(ParameterListScope)
 DEFINE_GET_CLASS_NAME(FunctionBodyScope)
 DEFINE_GET_CLASS_NAME(DefaultArgumentInitializerScope)
-DEFINE_GET_CLASS_NAME(AttachedPropertyWrapperScope)
+DEFINE_GET_CLASS_NAME(CustomAttributeScope)
 DEFINE_GET_CLASS_NAME(PatternEntryDeclScope)
 DEFINE_GET_CLASS_NAME(PatternEntryInitializerScope)
 DEFINE_GET_CLASS_NAME(ConditionalClausePatternUseScope)

lib/AST/ASTScopeCreation.cpp

@@ -180,7 +180,7 @@ class ScopeCreator final : public ASTAllocated<ScopeCreator> {
   addChildrenForParsedAccessors(AbstractStorageDecl *asd,
                                 ASTScopeImpl *parent);
 
-  void addChildrenForKnownAttributes(ValueDecl *decl,
+  void addChildrenForKnownAttributes(Decl *decl,
                                      ASTScopeImpl *parent);
 
   /// Add PatternEntryDeclScopes for each pattern binding entry.
@@ -569,7 +569,7 @@ void ScopeCreator::addChildrenForParsedAccessors(
   });
 }
 
-void ScopeCreator::addChildrenForKnownAttributes(ValueDecl *decl,
+void ScopeCreator::addChildrenForKnownAttributes(Decl *decl,
                                                  ASTScopeImpl *parent) {
   SmallVector<DeclAttribute *, 2> relevantAttrs;
 
@@ -601,10 +601,8 @@ void ScopeCreator::addChildrenForKnownAttributes(ValueDecl *decl,
             parent, specAttr, afd);
       }
     } else if (auto *customAttr = dyn_cast<CustomAttr>(attr)) {
-      if (auto *vd = dyn_cast<VarDecl>(decl)) {
-        constructExpandAndInsert<AttachedPropertyWrapperScope>(
-            parent, customAttr, vd);
-      }
+      constructExpandAndInsert<CustomAttributeScope>(
+          parent, customAttr, decl);
     }
   }
 }
@@ -716,7 +714,7 @@ CREATES_NEW_INSERTION_POINT(ConditionalClausePatternUseScope)
 
 NO_NEW_INSERTION_POINT(FunctionBodyScope)
 NO_NEW_INSERTION_POINT(AbstractFunctionDeclScope)
-NO_NEW_INSERTION_POINT(AttachedPropertyWrapperScope)
+NO_NEW_INSERTION_POINT(CustomAttributeScope)
 NO_NEW_INSERTION_POINT(EnumElementScope)
 NO_NEW_INSERTION_POINT(GuardStmtBodyScope)
 NO_NEW_INSERTION_POINT(ParameterListScope)
@@ -1177,7 +1175,7 @@ void DefaultArgumentInitializerScope::
   scopeCreator.addToScopeTree(initExpr, this);
 }
 
-void AttachedPropertyWrapperScope::
+void CustomAttributeScope::
     expandAScopeThatDoesNotCreateANewInsertionPoint(
         ScopeCreator &scopeCreator) {
   if (auto *args = attr->getArgs()) {
@@ -1192,7 +1190,9 @@ ASTScopeImpl *GenericTypeOrExtensionWholePortion::expandScope(
     GenericTypeOrExtensionScope *scope, ScopeCreator &scopeCreator) const {
   // Get now in case recursion emancipates scope
   auto *const ip = scope->getParent().get();
-
+
+  scopeCreator.addChildrenForKnownAttributes(scope->getDecl(), scope);
+
   auto *context = scope->getGenericContext();
   auto *genericParams = (isa<TypeAliasDecl>(context)
                          ? context->getParsedGenericParams()